Organic Electronic Device Comprising an Inverse Coordination Complex and a Method for Preparing the Same

ABSTRACT

The present invention relates to an organic electronic device comprising at least one inverse coordination complex, the N inverse coordination complex comprising: (i) a core consisting of one atom or of a plurality of atoms forming together a covalent cluster; (ii) a first coordination sphere consisting of at least four electropositive atoms having each individually an electronegativity according to Allen of less than 2,4; and (iii) a second coordination sphere comprising a plurality of ligands; wherein the first coordination sphere is closer to the core than the second coordination sphere; and all atoms of the core have a higher electronegativity according to Allen than any of the electropositive atoms of the first coordination sphere and a method for preparing the same.

The present invention relates to an organic electronic device comprisingan inverse coordination complex and a method for preparing the same.

BACKGROUND ART

Organic light-emitting diodes (OLEDs), which are self-emitting devices,have a wide viewing angle, excellent contrast, quick response, highbrightness, excellent driving voltage characteristics, and colorreproduction. A typical OLED includes an anode, a hole transport layer(HTL), an emission layer (EML), an electron transport layer (ETL), and acathode, which are sequentially stacked on a substrate. In this regard,the HTL, the EML, and the ETL are thin films formed from organic and/ororganometallic compounds.

When a voltage is applied to the anode and the cathode, holes injectedfrom the anode electrode move to the EML, via the HTL, and electronsinjected from the cathode electrode move to the EML, via the ETL. Theholes and electrons recombine in the EML to generate excitons. When theexcitons drop from an excited state to a ground state, light is emitted.The injection and flow of holes and electrons should be balanced, sothat an OLED having the above-described structure has excellentefficiency.

WO 2012/005615 discloses zinc complexes with photoluminescent propertieswherein in the complexes a central oxide dianion is tetrahedrallycoordinated with four Zn cations.

However, there is still a need to improve the performance of electronicdevices, in particular to select suitable materials to be comprised inorganic charge transport layers, organic charge injection layers orcharge generating layers thereof.

It is, therefore, the object of the present invention to provide anelectronic device and a method for preparing the same overcomingdrawbacks of the prior art, in particular to provide electronic devicescomprising novel organic charge transport materials, an organic chargeinjection materials or a charge generating materials, for improving theperformance of the device, in particular for reducing operationalvoltage and/or improving efficiency, in particular in OLEDs.

SUMMARY OF THE INVENTION

The above object is achieved by an organic electronic device comprisingat least one inverse coordination complex, the inverse coordinationcomplex comprising: (i) a core consisting of one atom or of a pluralityof atoms forming together a covalent cluster; (ii) a first coordinationsphere consisting of at least four electropositive atoms having eachindividually an electronegativity according to Allen of less than 2.4;and (iii) a second coordination sphere comprising a plurality ofligands; wherein the first coordination sphere is closer to the corethan the second coordination sphere; all atoms of the core have a higherelectronegativity according to Allen than any of the electropositiveatoms of the first coordination sphere; and at least one ligand of thesecond coordination sphere is covalently bound to at least two atoms ofthe first coordination sphere.

With regard to interatomic interaction which is typically mirrored byequilibrium distance between the interacting atoms, the relationshipbetween the core and the first coordination sphere in inversecoordination complexes is the same as in normal coordination complexes.In other words, in couples of closest atoms of the entire complex,wherein the first atom of the couple belongs to the core and the secondatom of the couple belongs to the first coordination sphere, thedistance between the first and the second atom is equal to or shorterthan the sum of van der Waals radii of the first and of the second atom.The term “inverse” encompasses the circumstance that whereas in normalcomplexes an electropositive central atom is surrounded by moreelectronegative atoms of respective ligands, in inverse coordinationcomplexes, the electronegative atoms of the core are surrounded by moreelectropositive atoms of the first coordination sphere.

It was surprisingly found by the inventors that an electronic devicecomprising the inverse coordination complex as defined above in a chargeinjection layer, a charge transport layer or a charge generating layerthereof shows superior properties over devices of the prior art, inparticular with respect to operational voltage and quantum efficiency.Particular advantages were achieved when the charge is a positivecharge, i.e. the charge injection/transport/generating layer is a holeinjection/transport/generating layer. Further advantages are apparentfrom the specific examples presented herein.

In the organic electronic device, the inverse coordination complex maybe electrically neutral. In this way, fine tuning of the electronicstructure of the inventive inverse coordination complex is achieved toimprove the usability thereof in charge injection layers, chargetransport layers or charge generating layers of electronic devices, inparticular in hole injection layer, hole transport layers and holegenerating layers.

In the organic electronic device, the electropositive atoms of the firstcoordination sphere may be independently selected from atoms havingelectronegativity according to Allen of less than 2.3, alternativelyless than 2.2, alternatively less than 2.1, alternatively less than 2.0,alternatively less than 1.9. In this way, fine tuning of the electronicstructure of the inventive inverse coordination complex is achieved toimprove the usability thereof in charge injection layers, chargetransport layers or charge generating layers of electronic devices, inparticular in hole injection layer, hole transport layers and holegenerating layers.

In the organic electronic device, the electropositive atoms may beindependently selected from metal ions in the oxidation state (II),alternatively from transition metals of the fourth period of thePeriodic Table of Elements in the oxidation state (II), alternativelyfrom Ti, Cr, Mn, Fe, Co, Ni, Zn, and Cu in the oxidation state (II);alternatively from Mn(II), Fe(II), Co(II), Ni(II) and Zn(II);alternatively the electropositive atoms are each Zn(II). In this way,fine tuning of the electronic structure of the inventive inversecoordination complex is achieved to improve the usability thereof incharge injection layers, charge transport layers or charge generatinglayers of electronic devices, in particular in hole injection layer,hole transport layers and hole generating layers.

In the organic electronic device, the atoms of the core may haveelectronegativity according to Allen of more than 1.7, alternativelymore than 1.8, alternatively more than 1.9, alternatively more than 2.0,alternatively more than 2.1, alternatively more than 2.2, alternativelymore than 2.3, alternatively more than 2.4. In this way, fine tuning ofthe electronic structure of the inventive inverse coordination complexis achieved to improve the usability thereof in charge injection layers,charge transport layers or charge generating layers of electronicdevices, in particular in hole injection layer, hole transport layersand hole generating layers.

In the organic electronic device, the core may consist of one atom. Inthis way, fine tuning of the electronic structure of the inventiveinverse coordination complex is achieved to improve the usabilitythereof in charge injection layers, charge transport layers or chargegenerating layers of electronic devices, in particular in hole injectionlayer, hole transport layers and hole generating layers.

In the organic electronic device, the core atom may be in a negativeoxidation state. In this way, fine tuning of the electronic structure ofthe inventive inverse coordination complex is achieved to improve theusability thereof in charge injection layers, charge transport layers orcharge generating layers of electronic devices, in particular in holeinjection layer, hole transport layers and hole generating layers.

In the organic electronic device, the atoms of the core may be selectedfrom chalcogen atoms in the oxidation state (-II), alternatively theatoms of the core may be independently selected from O, S, Se and Terespectively in the oxidation state (-II), alternatively from O(II) andS(-II), alternatively are O(-II). In this way, fine tuning of theelectronic structure of the inventive inverse coordination complex isachieved to improve the usability thereof in charge injection layers,charge transport layers or charge generating layers of electronicdevices, in particular in hole injection layer, hole transport layersand hole generating layers.

In the organic electronic device, the core may consist of one atom whichmay be O in the oxidation state (-II). In this way, fine tuning of theelectronic structure of the inventive inverse coordination complex isachieved to improve the usability thereof in charge injection layers,charge transport layers or charge generating layers of electronicdevices, in particular in hole injection layer, hole transport layersand hole generating layers.

In the organic electronic device, the first coordination sphere mayconsist of four electropositive atoms which may have anelectronegativity according to Allen of less than 2.4, respectively inthe oxidation state (II), and the four electropositive atoms may betetrahedrally coordinated to the core. In this way, fine tuning of theelectronic structure of the inventive inverse coordination complex isachieved to improve the usability thereof in charge injection layers,charge transport layers or charge generating layers of electronicdevices, in particular in hole injection layer, hole transport layersand hole generating layers.

In the organic electronic device, the at least one ligand of the secondcoordination sphere, which bridges two electropositive atoms of thefirst coordination sphere, may be a bidentate anionic ligand formed bydeprotonation of an alpha-gamma tautomerizable protic acid. Examples ofalpha-gamma tautomerizable protic acids are carboxylic acids orsulfonamides comprising at least one proton bound to the nitrogen atompf the amide group. Another example of an alpha-gamma tautomerizableprotic acid is nitric acid.

In the organic electronic device, the ligands may be independentlyselected from carboxylate anions, nitrate anions and sulfonyl amideanions. In this way, fine tuning of the electronic structure of theinventive inverse coordination complex is achieved to improve theusability thereof in charge injection layers, charge transport layers orcharge generating layers of electronic devices, in particular in holeinjection layer, hole transport layers and hole generating layers.

In the organic electronic device, the ligands of the second coordinationsphere may be represented by the general formula (I)

wherein R¹ and R² are independently selected from the groups, consistingof C₁ to C₃₀ hydrocarbyl groups and C₂ to C₃₀ heterocyclic group,wherein R¹ and/ or R² may optionally be substituted with at least one ofCN, F, Cl, Br and I. In this way, fine tuning of the electronicstructure of the inventive inverse coordination complex is achieved toimprove the usability thereof in charge injection layers, chargetransport layers or charge generating layers of electronic devices, inparticular in hole injection layer, hole transport layers and holegenerating layers.

In the organic electronic device, the core may consist of one chalcogenatom selected from O, S, Se and Te in the oxidation state (-II); thefirst oxidation sphere may consists of four electropositive atoms whichmay be four metal atoms in the oxidation state (II) and which may betetrahedrally coordinated to the core, and the second coordinationsphere may consists of six ligands having the general formula (I). Inthis way, fine tuning of the electronic structure of the inventiveinverse coordination complex is achieved to improve the usabilitythereof in charge injection layers, charge transport layers or chargegenerating layers of electronic devices, in particular in hole injectionlayer, hole transport layers and hole generating layers.

In the organic electronic device, each ligand of the second coordinationsphere may be coordinated to two different metal atoms of the firstcoordination sphere. In this way, fine tuning of the electronicstructure of the inventive inverse coordination complex is achieved toimprove the usability thereof in charge injection layers, chargetransport layers or charge generating layers of electronic devices, inparticular in hole injection layer, hole transport layers and holegenerating layers.

The organic electronic device may, between a first electrode and asecond electrode, comprise an organic semiconducting layer comprisingthe at least one inverse coordination complex.

In the organic electronic device, the organic semiconducting layer maybe a charge injection layer, a charge transport layer or a chargegeneration layer.

In the organic semiconducting device, the organic semiconducting layermay be a hole injection layer, a hole transport layer or a holegeneration layer.

In the organic electronic device, the organic semiconducting layer mayfurther comprise at least one organic matrix compound. The organicmatrix compound may be a charge transport matrix and the inversecoordination complex may be an electrical dopant. The charge transportmatrix may be a hole transport matrix.

The organic semiconducting device may further comprise at least onelight emitting layer.

The organic electronic device may be an electroluminescent device. Theelectroluminescent device may be an organic light emitting diode.

Finally, the object is achieved by a method for preparing the inventiveorganic electronic device, the method comprising the steps of (a)evaporating the inverse coordination complex; and (b) depositing theinverse coordination complex on a solid support.

In the method, evaporation may be at elevated temperature and/or reducedpressure.

Furthermore, in the inventive method, the vaporizing and the depositingmay respectively comprise co-vaporizing and co-depositing of thecoordination complex with a matrix material.

Furthermore, the inventive method may comprise further process steps, inparticular deposition of further layers suitable to be comprised in anorganic electronic device.

With respect to the inverse coordination complexes comprised in theabove organic semiconducting device, such inverse coordination complexeshaving a core consisting of a single O or F atom and in which the firstcoordination sphere comprises a H atom may be excluded.

Likewise, such inverse coordination complexes wherein the core consistsof a single O or F atom and wherein the first coordination sphereconsists of H atoms may be excluded.

In the following, the present invention will be explained referring toone specific embodiment.

DETAILED DESCRIPTION OF THE INVENTION

A zinc complex having composition M²L₂ and supposed structure E₂, withan electron withdrawing ligand L with a perfluorphenyl group bound to anitrogen, has been prepared. Further detailed studies on E₂, however,revealed that its sublimation is in fact accompanied by a chemicalchange, because the sublimed complex differs in its structure andcomposition from the starting material. More specifically, the sublimedmaterial partly formed monocrystals of a size and quality suitable forX-ray diffraction (XRD), the structure and composition of this material,assigned herein as E₃, has been fully resolved by this method.

The XRD revealed that the sublimed material has an unexpectedcomposition Zn₄OL₆ and a cluster structure E₃ shown in FIG. 4.

Due to complexity of this molecule E₃ having summary formulaC₄₂F₄₈N₆O₁₃S₆Zn₄, the structure shall be described in the next paragraphin form of a guide:

The molecule consists of the central oxide dianion, tetrahedrallycoordinated with four Zn dications, bridged with six monoanionic ligandsL (which are per se structurally identical as in formula E₂) in the waythat on each edge of the central Zn₄ tetrahedron, one L is bound to bothZn cations through its N and O atoms, respectively, forming thus withboth Zn cations and the central oxide dianion a six-membered—Zn—O—Zn—N—S—O— ring.

In the present application, the prior art compound B2

(LiTFSI), CAS 90076-65-6),

known for use in organic light emitting diodes of the prior art, inparticular in hole injection materials thereof or as p-dopant, has beenused as the reference material to show superiority of the inventivematerials.

Further Layers

In accordance with the invention, the electronic device may comprise,besides the layers already mentioned above, further layers. Exemplaryembodiments of respective layers are described in the following:

Substrate

The substrate may be any substrate that is commonly used inmanufacturing of, electronic devices, such as organic light-emittingdiodes. If light is to be emitted through the substrate, the substrateshall be a transparent or semitransparent material, for example a glasssubstrate or a transparent plastic substrate. If light is to be emittedthrough the top surface, the substrate may be both a transparent as wellas a non-transparent material, for example a glass substrate, a plasticsubstrate, a metal substrate or a silicon substrate.

Anode Electrode

Either the first electrode or the second electrode may be an anodeelectrode. The anode electrode may be formed by depositing or sputteringa material that is used to form the anode electrode. The material usedto form the anode electrode may be a high work-function material, so asto facilitate hole injection. The anode material may also be selectedfrom a low work function material (i.e. aluminum). The anode electrodemay be a transparent or reflective electrode. Transparent conductiveoxides, such as indium tin oxide (ITO), indium zinc oxide (IZO),tin-dioxide (SnO2), aluminum zinc oxide (AlZO) and zinc oxide (ZnO), maybe used to form the anode electrode. The anode electrode may also beformed using metals, typically silver (Ag), gold (Au), or metal alloys.

Hole Injection Layer

In accordance with the invention, the hole injection layer may compriseor consist of an inverse coordination complex as described above in verydetail. The hole injection layer (HIL) may be formed on the anodeelectrode by vacuum deposition, spin coating, printing, casting,slot-die coating, Langmuir-Blodgett (LB) deposition, or the like. Whenthe HIL is formed using vacuum deposition, the deposition conditions mayvary according to the compound that is used to form the HIL, and thedesired structure and thermal properties of the HIL. In general,however, conditions for vacuum deposition may include a depositiontemperature of 100° C. to 500° C., a pressure of 10⁻⁸ to 10⁻³ Torr (1Torr equals 133.322 Pa), and a deposition rate of 0.1 to 10 nm/sec.

When the HIL is formed using spin coating or printing, coatingconditions may vary according to the compound that is used to form theHIL, and the desired structure and thermal properties of the HIL. Forexample, the coating conditions may include a coating speed of about2000 rpm to about 5000 rpm, and a thermal treatment temperature of about80° C. to about 200° C. Thermal treatment removes a solvent after thecoating is performed.

The HIL may be formed—if the electronic device comprises besides thehole injection layer and/or a hole generating layer and the holetransport layer and/or the hole generating layer comprises the inversecoordination complex—of any compound that is commonly used to form aHIL. Examples of compounds that may be used to form the HIL include aphthalocyanine compound, such as copper phthalocyanine (CuPc),4,4′,4″-tris (3-methylphenylphenylamino) triphenylamine (m-MTDATA),TDATA, 2T-NATA, polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS).polyaniline/camphor sulfonic acid (Pani/CSA), andpolyaniline)/poly(4-styrenesulfonate (PANI/PSS).

In such a case, the HIL may be a pure layer of p-dopant or may beselected from a hole-transporting matrix compound doped with a p-dopant.Typical examples of known redox doped hole transport materials are:copper phthalocyanine (CuPc), which HOMO level is approximately −5.2 eV,doped with tetrafluoro-tetracyanoquinonedimethane (F4TCNQ), which LUMOlevel is about −5.2 eV; zinc phthalocyanine (ZnPc) (HOMO=−5.2 eV) dopedwith F4TCNQ; α-NPD(N,N′-Bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine) doped withF4TCNQ. α-NPD doped with 2,2′-(perfluoronaphthalen-2,6-diylidene)dimalononitrile (PD1). α-NPD doped with2,2′,2″-(cyclopropane-1,2,3-triylidene)tris(2-(p-cyanotetrafluorophenyl)acetonitrile)(PD2). Dopant concentrations can be selected from 1 to 20 wt.-%, morepreferably from 3 wt.-% to 10 wt.-%.

The thickness of the HIL may be in the range from about 1 nm to about100 nm, and for example, from about 1 nm to about 25 nm. When thethickness of the HIL is within this range, the HIL may have excellenthole injecting characteristics, without a substantial penalty in drivingvoltage.

Hole Transport Layer

In accordance with the invention, the hole transport layer may compriseor consist of the inverse coordination complex as described above indetail.

The hole transport layer (HTL) may be formed on the HIL by vacuumdeposition, spin coating, slot-die coating, printing, casting,Langmuir-Blodgett (LB) deposition, or the like. When the HTL is formedby vacuum deposition or spin coating, the conditions for deposition andcoating may be similar to those for the formation of the HIL. However,the conditions for the vacuum or solution deposition may vary, accordingto the compound that is used to form the HTL.

In case that the HTL does not comprise an inverse coordination complexin accordance with the invention, but the inverse coordination complexis comprised in the HIL and/or the CGL, the HTL may be formed by anycompound that is commonly used to form a HTL. Compounds that can besuitably used are disclosed for example in Yasuhiko Shirota and HiroshiKageyama, Chem. Rev. 2007, 107, 953-1010 and incorporated by reference.Examples of the compound that may be used to form the HTL are: carbazolederivatives, such as N-phenylcarbazole or polyvinylcarbazole; benzidinederivatives, such asN,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD), or N,N′-di(naphthalen-1-yl)-N,N′-diphenyl benzidine (alpha-NPD);and triphenylamine-based compound, such as4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA). Among these compounds,TCTA can transport holes and inhibit excitons from being diffused intothe EML.

The thickness of the HTL may be in the range of about 5 nm to about 250nm, preferably, about 10 nm to about 200 nm, further about 20 nm toabout 190 nm, further about 40 nm to about 180 nm, further about 60 nmto about 170 nm, further about 80 nm to about 160 nm, further about 100nm to about 160 nm, further about 120 nm to about 140 nm. A preferredthickness of the HTL may be 170 nm to 200 nm.

When the thickness of the HTL is within this range, the HTL may haveexcellent hole transporting characteristics, without a substantialpenalty in driving voltage.

Electron Blocking Layer

The function of the electron blocking layer (EBL) is to preventelectrons from being transferred from the emission layer to the holetransport layer and thereby confine electrons to the emission layer.Thereby, efficiency, operating voltage and/or lifetime are improved.Typically, the electron blocking layer comprises a triarylaminecompound. The triarylamine compound may have a LUMO level closer tovacuum level than the LUMO level of the hole transport layer. Theelectron blocking layer may have a HOMO level that is further away fromvacuum level compared to the HOMO level of the hole transport layer. Thethickness of the electron blocking layer may be selected between 2 and20 nm.

The electron blocking layer may comprise a compound of formula Z below(Z).

In Formula Z, CY₁ and CY₂ are the same as or different from each other,and each independently represent a benzene cycle or a naphthalene cycle,Ar₁ to Ar₃ are the same as or different from each other, and eachindependently selected from the group consisting of hydrogen; asubstituted or unsubstituted aryl group having 6 to 30 carbon atoms; anda substituted or unsubstituted heteroaryl group having 5 to 30 carbonatoms, Ar₄ is selected from the group consisting of a substituted orunsubstituted phenyl group, a substituted or unsubstituted biphenylgroup, a substituted or unsubstituted terphenyl group, a substituted orunsubstituted triphenylene group, and a substituted or unsubstitutedheteroaryl group having 5 to 30 carbon atoms, L is a substituted orunsubstituted arylene group having 6 to 30 carbon atoms.

If the electron blocking layer has a high triplet level, it may also bedescribed as triplet control layer.

The function of the triplet control layer is to reduce quenching oftriplets if a phosphorescent green or blue emission layer is used.Thereby, higher efficiency of light emission from a phosphorescentemission layer can be achieved. The triplet control layer is selectedfrom triarylamine compounds with a triplet level above the triplet levelof the phosphorescent emitter in the adjacent emission layer. Suitablecompounds for the triplet control layer, in particular the triarylaminecompounds, are described in EP 2 722 908 A1.

Emission Layer (EML)

The EML may be formed on the HTL by vacuum deposition, spin coating,slot-die coating, printing, casting, LB deposition, or the like. Whenthe EML is formed using vacuum deposition or spin coating, theconditions for deposition and coating may be similar to those for theformation of the HIL. However, the conditions for deposition and coatingmay vary, according to the compound that is used to form the EML.

The emission layer (EML) may be formed of a combination of a host and anemitter dopant. Example of the host are Alq3,4,4′-N,N′-dicarbazole-biphenyl (CBP), poly(n-vinylcarbazole) (PVK),9,10-di(naphthalene-2-yl)anthracene (ADN),4,4′,4″-tris(carbazol-9-yl)-triphenylamine(TCTA),1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBI),3-tert-butyl-9,10-di-2-naphthylanthracenee (TBADN), distyrylarylene(DSA), bis(2-(2-hydroxyphenyl)benzo-thiazolate)zinc (Zn(BTZ)₂), G3below, AND Compound 1 below, and Compound 2 below.

The emitter dopant may be a phosphorescent or fluorescent emitter.Phosphorescent emitters and emitters which emit light via a thermallyactivated delayed fluorescence (TADF) mechanism may be preferred due totheir higher efficiency. The emitter may be a small molecule or apolymer.

Examples of red emitter dopants are PtOEP, Ir(piq)₃, Btp₂lr(acac), butare not limited thereto. These compounds are phosphorescent emitters,however, fluorescent red emitter dopants could also be used.

Examples of phosphorescent green emitter dopants are Ir(ppy)₃(ppy=phenylpyridine), Ir(ppy)₂(acac), Ir(mpyp)₃ are shown below.Compound 3 is an example of a fluorescent green emitter and thestructure is shown below.

Examples of phosphorescent blue emitter dopants are F2Irpic,(F2ppy)2Ir(tmd) and Ir(dfppz)3, ter-fluorene, the structures are shownbelow. 4,4′-bis(4-diphenyl amiostyryl)biphenyl (DPAVBi),2,5,8,11-tetra-tert-butyl perylene (TBPe), and Compound 4 below areexamples of fluorescent blue emitter dopants.

The amount of the emitter dopant may be in the range from about 0.01 toabout 50 parts by weight, based on 100 parts by weight of the host.Alternatively, the emission layer may consist of a light-emittingpolymer. The EML may have a thickness of about 10 nm to about 100 nm,for example, from about 20 nm to about 60 nm. When the thickness of theEML is within this range, the EML may have excellent light emission,without a substantial penalty in driving voltage.

Hole Blocking Layer (HBL)

A hole blocking layer (HBL) may be formed on the EML, by using vacuumdeposition, spin coating, slot-die coating, printing, casting, LBdeposition, or the like, in order to prevent the diffusion of holes intothe ETL. When the EML comprises a phosphorescent dopant, the HBL mayhave also a triplet exciton blocking function.

When the HBL is formed using vacuum deposition or spin coating, theconditions for deposition and coating may be similar to those for theformation of the HIL. However, the conditions for deposition and coatingmay vary, according to the compound that is used to form the HBL. Anycompound that is commonly used to form a HBL may be used. Examples ofcompounds for forming the HBL include oxadiazole derivatives, triazolederivatives, and phenanthroline derivatives.

The HBL may have a thickness in the range from about 5 nm to about 100nm, for example, from about 10 nm to about 30 nm. When the thickness ofthe HBL is within this range, the HBL may have excellent hole-blockingproperties, without a substantial penalty in driving voltage.

Electron Transport Layer (ETL)

The OLED according to the present invention may contain an electrontransport layer (ETL). The electron transport layer may comprise orconsist of the inventive inverse coordination complex.

According to various embodiments the OLED may comprises an electrontransport layer or an electron transport layer stack comprising at leasta first electron transport layer and at least a second electrontransport layer.

By suitably adjusting energy levels of particular layers of the ETL, theinjection and transport of the electrons may be controlled, and theholes may be efficiently blocked. Thus, the OLED may have long lifetime.

The electron transport layer of the electronic device may comprise anorganic electron transport matrix (ETM) material. Further, the electrontransport layer may comprise one or more n-dopants. Suitable compoundsfor the ETM are not particularly limited. In one embodiment, theelectron transport matrix compounds consist of covalently bound atoms.Preferably, the electron transport matrix compound comprises aconjugated system of at least 6, more preferably of at least 10delocalized electrons. In one embodiment, the conjugated system ofdelocalized electrons may be comprised in aromatic or heteroaromaticstructural moieties, as disclosed e.g. in documents EP 1 970 371 A1 orWO 2013/079217 A1.

Electron Injection Layer (EIL)

The optional EIL, which may facilitates injection of electrons from thecathode, may be formed on the ETL, preferably directly on the electrontransport layer. The electron injection layer may comprise or consistsof the inverse coordination complex. Examples of materials for formingthe EIL include lithium 8-hydroxyquinolinolate (LiQ), LiF, NaCl, CsF,Li₂O, BaO, Ca, Ba, Yb, Mg which are known in the art. Deposition andcoating conditions for forming the EIL are similar to those forformation of the HIL, although the deposition and coating conditions mayvary, according to the material that is used to form the EIL.

The thickness of the EIL may be in the range from about 0.1 nm to about10 nm, for example, in the range from about 0.5 nm to about 9 nm. Whenthe thickness of the EIL is within this range, the EIL may havesatisfactory electron-injecting properties, without a substantialpenalty in driving voltage.

Cathode Electrode

The cathode electrode is formed on the EIL if present. The cathodeelectrode may be formed of a metal, an alloy, an electrically conductivecompound, or a mixture thereof. The cathode electrode may have a lowwork function. For example, the cathode electrode may be formed oflithium (Li), magnesium (Mg), aluminum (Al), aluminum (Al)-lithium (Li),calcium (Ca), barium (Ba), ytterbium (Yb), magnesium (Mg)-indium (In),magnesium (Mg)-silver (Ag), or the like. Alternatively, the cathodeelectrode may be formed of a transparent conductive oxides, such as ITOor IZO.

The thickness of the cathode electrode may be in the range from about 5nm to about 1000 nm, for example, in the range from about 10 nm to about100 nm. When the thickness of the cathode electrode is in the range fromabout 5 nm to about 50 nm, the cathode electrode may be transparent orsemitransparent even if formed from a metal or metal alloy.

It is to be understood that the cathode electrode is not part of anelectron injection layer or the electron transport layer.

Charge Generation Layer/Hole Generating Layer

The charge generation layer (CGL) may be composed of a double layer. Thecharge generation layer, the n-type charge generation layer as well asthe hole generation layer, may comprise or consist of the inversecoordination complex.

Typically, the charge generation layer is a pn junction joining a n-typecharge generation layer (electron generating layer) and a holegenerating layer. The n-side of the pn junction generates electrons andinjects them into the layer which is adjacent in the direction to theanode. Analogously, the p-side of the p-n junction generates holes andinjects them into the layer which is adjacent in the direction to thecathode.

Charge generating layers are used in tandem devices, for example, intandem OLEDs comprising, between two electrodes, two or more emissionlayers. In aa tandem OLED comprising two emission layers, the n-typecharge generation layer provides electrons for the first light emissionlayer arranged near the anode, while the hole generating layer providesholes to the second light emission layer arranged between the firstemission layer and the cathode.

In accordance with the invention, it may be provided that the electronicdevice comprises a hole injection layer as well as a hole generatinglayer. If the hole injection layer comprises the inverse coordinationcomplex, it is not obligatory that also the hole generating layercomprises the inverse coordination complex. In such a case, the holegenerating layer can be composed of an organic matrix material dopedwith p-type dopant. Suitable matrix materials for the hole generatinglayer may be materials conventionally used as hole injection and/or holetransport matrix materials. Also, p-type dopant used for the holegenerating layer can employ conventional materials. For example, thep-type dopant can be one selected from a group consisting oftetrafluore-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), derivatives oftetracyanoquinodimethane, radialene derivatives, iodine, FeCl3, FeF3,and SbCl5. Also, the host can be one selected from a group consisting ofN,N′-di(naphthalen-1-yl)-N,N-diphenyl-benzidine (NPB),N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1-biphenyl-4,4′-diamine (TPD)and N,N′,N′-tetranaphthyl-benzidine (TNB).

In a preferred embodiment, the hole generating layer comprises orconsists of the inverse coordination complex as defined above in detail.

The n-type charge generation layer can be layer of a neat n-dopant, forexample of an electropositive metal, or can consist of an organic matrixmaterial doped with the n-dopant. In one embodiment, the n-type dopantcan be alkali metal, alkali metal compound, alkaline earth metal, oralkaline earth metal compound. In another embodiment, the metal can beone selected from a group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr,Ba, La, Ce, Sm, Eu, Tb, Dy, and Yb. More specifically, the n-type dopantcan be one selected from a group consisting of Cs, K, Rb, Mg, Na, Ca,Sr, Eu and Yb. Suitable matrix materials for the electron generatinglayer may be the materials conventionally used as matrix materials forelectron injection or electron transport layers. The matrix material canbe for example one selected from a group consisting of triazinecompounds, hydroxyquinoline derivatives liketris(8-hydroxyquinoline)aluminum, benzazole derivatives, and silolederivatives.

In one embodiment, the n-type charge generation layer may includecompounds of the following Chemical Formula X.

wherein each of A1 to A6 may be hydrogen, a halogen atom, nitrile (—CN),nitro (—NO2), sulfonyl (—SO2R), sulfoxide (—SOR), sulfonamide (—SO2NR),sulfonate (—SO3R), trifluoromethyl (—CF3), ester (—COOR), amide (—CONHRor —CONRR′), substituted or unsubstituted straight-chain orbranched-chain C1-C12 alkoxy, substituted or unsubstitutedstraight-chain or branched-chain C1-C12 alkyl, substituted orunsubstituted straight-chain or branched chain C2-C12 alkenyl, asubstituted or unsubstituted aromatic or non-aromatic heteroring,substituted or unsubstituted aryl, substituted or unsubstituted mono- ordi-arylamine, substituted or unsubstituted aralkylamine, or the like.Herein, each of the above R and R′ may be substituted or unsubstitutedC1-C60 alkyl, substituted or unsubstituted aryl, or a substituted orunsubstituted 5- to 7-membered heteroring, or the like.

An example of such n-type charge generation layer may be a layercomprising CNHAT

The hole generating layer is arranged on top of the n-type chargegeneration layer.

Organic Light-Emitting Diode (OLED)

According to one aspect of the present invention, there is provided anorganic light-emitting diode (OLED) comprising: a substrate; an anodeelectrode formed on the substrate; a hole injection layer, a holetransport layer, an emission layer, and a cathode electrode.

According to another aspect of the present invention, there is providedan OLED comprising: a substrate; an anode electrode formed on thesubstrate; a hole injection layer, a hole transport layer, an electronblocking layer, an emission layer, a hole blocking layer and a cathodeelectrode.

According to another aspect of the present invention, there is providedan OLED comprising: a substrate; an anode electrode formed on thesubstrate; a hole injection layer, a hole transport layer, an electronblocking layer, an emission layer, a hole blocking layer, an electrontransport layer, and a cathode electrode.

According to another aspect of the present invention, there is providedan OLED comprising: a substrate; an anode electrode formed on thesubstrate; a hole injection layer, a hole transport layer, an electronblocking layer, an emission layer, a hole blocking layer, an electrontransport layer, an electron injection layer, and a cathode electrode.

According to various embodiments of the present invention, there may beprovided OLEDs comprising layers arranged between the above mentionedlayers, on the substrate or on the top electrode.

According to one aspect, the OLED can comprise a layer structure of asubstrate that is adjacent arranged to an anode electrode, the anodeelectrode is adjacent arranged to a first hole injection layer, thefirst hole injection layer is adjacent arranged to a first holetransport layer, the first hole transport layer is adjacent arranged toa first electron blocking layer, the first electron blocking layer isadjacent arranged to a first emission layer, the first emission layer isadjacent arranged to a first electron transport layer, the firstelectron transport layer is adjacent arranged to an n-type chargegeneration layer, the n-type charge generation layer is adjacentarranged to a hole generating layer, the hole generating layer isadjacent arranged to a second hole transport layer, the second holetransport layer is adjacent arranged to a second electron blockinglayer, the second electron blocking layer is adjacent arranged to asecond emission layer, between the second emission layer and the cathodeelectrode an optional electron transport layer and/or an optionalinjection layer are arranged.

For example, the OLED according to FIG. 2 may be formed by a process,wherein

on a substrate (110), an anode (120), a hole injection layer (130), ahole transport layer (140), an electron blocking layer (145), anemission layer (150), a hole blocking layer (155), an electron transportlayer (160), an electron injection layer (180) and the cathode electrode(190) are subsequently formed in that order.

Details and Definitions of the Invention

The present invention is related to an organic electronic device. Thedevice comprises a first electrode and a second electrode. Between thefirst electrode and the second electrode, at least one hole injectionlayer and/or at least one hole transport layer and/or at least one holegenerating layer is arranged. That is, the electronic device may onlycomprise a hole injection layer between the first electrode and thesecond electrode. Likewise, the inventive electronic device may onlycomprise the hole transport layer between the first electrode and thesecond electrode. Likewise, the inventive electronic device may onlycomprise the hole generating layer between the first electrode and thesecond electrode. Likewise, the electronic device may comprise only twoor all three of the above hole injection, hole transport or holegenerating layers between the first electrode and the second electrode.In case that electronic device only comprises the hole injection layer(and not the hole generating layer) it is provided that the holeinjection layer consists of the inverse coordination complex. Likewise,in the case that the electronic device comprises only the holegenerating layer (and not the hole injection layer) it is provided thatthe hole generating layer consists of the inverse coordination complex.In case that the electronic device comprises both the hole injectionlayer and the hole generating layer, it may be provided that only thehole injection layer consists of the inverse coordination complex, thatonly the hole generating layer consists of the inverse coordinationcomplex or that both the hole injection layer and the hole generatinglayer consist of the inverse coordination complex.

In the above definition of the invention, reference is made to theelectronegativity values according to Allen. According to Allen, theelectronegativity of an atom is related to the average energy of thevalence electrons in a free atom thereof. The electronegativity valuesaccording to Allen are as follows. For lanthanide elements La, Ce, Pr,Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, it is assumed that Allenelectronegativity is less than 1.15, for Th and U, it is assumed thatAllen electronegativity is less than 1.5.

Electronegativity using the Allen scale Group 1 2 3 4 5 6 7 8 9 10 11 1213 14 15 16 17 18 Period 1 H He 2.300 4.160 2 Li Be B C N O F Ne 0.9121.576 2.051 2.544 3.066 3.610 4.193 4.787 3 Na Mg Al Si P S Cl Ar 0.8691.293 1.613 1.916 2.253 2.589 2.869 3.242 4 K Ca Sc Ti V Cr Mn Fe Co NiCu Zn Ga Ge As Se Br Kr 0.734 1.034 1.19 1.38 1.53 1.65 1.75 1.80 1.841.88 1.85 1.59 1.756 1.994 2.211 2.424 2.685 2.966 5 Rb Sr Y Zr Nb Mo TcRu Rh Pd Ag Cd In Sn Sb Te I Xe 0.706 0.963 1.12 1.32 1.41 1.47 1.511.54 1.56 1.58 1.87 1.52 1.656 1.824 1.984 2.158 2.359 2.582 6 Cs Ba LuHf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 0.659 0.881 1.09 1.16 1.341.47 1.60 1.65 1.68 1.72 1.92 1.76 1.789 1.854 2.01 2.19 2.39 2.60 7 FrRa 0.67 0.89

In terms of the present invention, a “covalent cluster” comprises of atleast two atoms bound to each other via a covalent chemical bond. Itmay, of course, be provided that the covalent cluster comprises morethan two atoms provided that all of the atoms are connected with eachother via covalent bonds.

In general terms, a coordination complex refers a compound having theformula ML_(n) in which one metal-ion or atom M is surrounded by one ormore ligands L. In such a case, the ligands L are normally bond to themetal M via a dative bond, i.e. via the electrons of a free electronpair of the ligand which is transferred into a free orbital of themetal. In terms of the present invention, an inverse coordinationcomplex is such a complex in which a core (normally having free electronpairs) is connected to a first coordination sphere of atoms having freeorbitals, normally metal atoms or ions. Therefore, referring to theabove formula, a coordination complex in terms of the presentapplication may be considered to have the structure—generic—XM_(n)wherein the electropositive elements M form the first coordinationsphere around an electronegative core X.

Electropositive in this regard refers to elements which have, accordingto Allen, a lower electronegativity than the atoms of the core.

With respect to the preferred electronegativity values mentioned above,it should be noted that, of course, these preferred values have alwaysto be read in context of claim 1. I.e. the requirement that all atoms ofthe core have a higher electronegativity according to Allen then any ofthe electropositive atoms of the first coordination sphere has always tobe fulfilled.

The term “hydrocarbyl group” as used herein shall be understood toencompass any organic group comprising carbon atoms, in particularorganic groups, such as alkyl, aryl, heteroaryl, heteroalkyl, inparticular such groups which are substituents usual in organicelectronics.

The term “alkyl” as used herein shall encompass linear as well asbranched and cyclic alkyl. For example, C₃-alkyl may be selected fromn-propyl and iso-propyl. Likewise, C₄-alkyl encompasses n-butyl,sec-butyl and t-butyl. Likewise, C₆-alkyl encompasses n-hexyl andcyclo-hexyl.

The subscribed number n in C_(n) relates to the total number of carbonatoms in the respective alkyl, arylene, heteroarylene or aryl group.

The term “aryl” as used herein shall encompass phenyl (C₆-aryl), fusedaromatics, such as naphthalene, anthracene, phenanthracene, tetraceneetc. Further encompassed are biphenyl and oligo- or polyphenyls, such asterphenyl etc. Further encompassed shall be any further aromatichydrocarbon substituents, such as fluorenyl etc. Arylene, respectivelyheteroarylene refers to groups to which two further moieties areattached.

The term “heteroaryl” as used herein refers to aryl groups in which atleast one carbon atom is substituted by a heteroatom, preferablyselected from N, O, S, B or Si.

The term “halogenated” refers to an organic compound in which onehydrogen atom thereof is replaced by a halogen atom. The term“perhalogenated” refers to an organic compound in which all of thehydrogen atoms thereof are replaced by halogen atoms. The meaning of theterms “fluorinated” and “perfluorinated” should be understoodanalogously.

The subscripted number n in C_(n)-heteroaryl merely refers to the numberof carbon atoms excluding the number of heteroatoms. In this context, itis clear that a C₃ heteroarylene group is an aromatic compoundcomprising three carbon atoms, such as pyrazol, imidazole, oxazole,thiazole and the like.

In terms of the invention, the expression “between” with respect to onelayer being between two other layers does not exclude the presence offurther layers which may be arranged between the one layer and one ofthe two other layers. In terms of the invention, the expression “indirect contact” with respect to two layers being in direct contact witheach other means that no further layer is arranged between those twolayers. One layer deposited on the top of another layer is deemed to bein direct contact with this layer.

With respect to the inventive organic semiconductive layer as well aswith respect to the inventive compound, the compounds mentioned in theexperimental part are most preferred.

The inventive electronic device may be an organic electroluminescentdevice (OLED) an organic photovoltaic device (OPV) or an organicfield-effect transistor (OFET).

According to another aspect, the organic electroluminescent deviceaccording to the present invention may comprise more than one emissionlayer, preferably two or three emission layers. An OLED comprising morethan one emission layer is also described as a tandem OLED or stackedOLED.

The organic electroluminescent device (OLED) may be a bottom- ortop-emission device.

Another aspect is directed to a device comprising at least one organicelectroluminescent device (OLED). A device comprising organiclight-emitting diodes is for example a display or a lighting panel.

In the present invention, the following defined terms, these definitionsshall be applied, unless a different definition is given in the claimsor elsewhere in this specification.

In the context of the present specification the term “different” or“differs” in connection with the matrix material means that the matrixmaterial differs in their structural formula.

The energy levels of the highest occupied molecular orbital, also namedHOMO, and of the lowest unoccupied molecular orbital, also named LUMO,are measured in electron volt (eV).

The terms “OLED” and “organic light-emitting diode” are simultaneouslyused and have the same meaning. The term “organic electroluminescentdevice” as used herein may comprise both organic light emitting diodesas well as organic light emitting transistors (OLETs).

As used herein, “weight percent”, “wt.-%”, “percent by weight”, “% byweight”, and variations thereof refer to a composition, component,substance or agent as the weight of that component, substance or agentof the respective electron transport layer divided by the total weightof the respective electron transport layer thereof and multiplied bytoo. It is under-stood that the total weight percent amount of allcomponents, substances and agents of the respective electron transportlayer and electron injection layer are selected such that it does notexceed 100 wt.-%.

As used herein, “volume percent”, “vol.-%”, “percent by volume”, “% byvolume”, and variations thereof refer to a composition, component,substance or agent as the volume of that component, substance or agentof the respective electron transport layer divided by the total volumeof the respective electron transport layer thereof and multiplied by100. It is understood that the total volume percent amount of allcomponents, substances and agents of the cathode layer are selected suchthat it does not exceed 100 vol.-%.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. As used herein, the term“about” refers to variation in the numerical quantity that can occur.Whether or not modified by the term “about” the claims includeequivalents to the quantities.

It should be noted that, as used in this specification and the appendedclaims, the singular forms “a”, “an”, and “the” include plural referentsunless the content clearly dictates otherwise.

The term “free of”, “does not contain”, “does not comprise” does notexclude impurities. Impurities have no technical effect with respect tothe object achieved by the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present invention willbecome apparent and more readily appreciated from the followingdescription of the exemplary embodiments, taken in conjunction with theaccompanying drawings, of which:

FIG. 1 is a schematic sectional view of an organic light-emitting diode(OLED), according to an exemplary embodiment of the present invention;

FIG. 2 is a schematic sectional view of an OLED, according to anexemplary embodiment of the present invention.

FIG. 3 is a schematic sectional view of a tandem OLED comprising acharge generation layer, according to an exemplary embodiment of thepresent invention.

FIG. 4 shows the crystal structure of the inventive inverse coordinationcomplex E₃, having the summary formula C₄₂F₄₈N₆O₁₃S₆Zn₄.

EMBODIMENTS OF THE INVENTIVE DEVICE

Reference will now be made in detail to the exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The exemplary embodiments are described below, in order toexplain the aspects of the present invention, by referring to thefigures.

Herein, when a first element is referred to as being formed or disposed“on” a second element, the first element can be disposed directly on thesecond element, or one or more other elements may be disposed therebetween. When a first element is referred to as being formed or disposed“directly on” a second element, no other elements are disposed therebetween.

FIG. 1 is a schematic sectional view of an organic light-emitting diode(OLED) 100, according to an exemplary embodiment of the presentinvention. The OLED 100 includes a substrate 110, an anode 120, a holeinjection layer (HIL) 130, a hole transport layer (HTL) 140, an emissionlayer (EML) 150, an electron transport layer (ETL) 160. The electrontransport layer (ETL) 160 is formed directly on the EML 150. Onto theelectron transport layer (ETL) 160, an electron injection layer (EIL)180 is disposed. The cathode 190 is disposed directly onto the electroninjection layer (EIL) 180.

Instead of a single electron transport layer 160, optionally an electrontransport layer stack (ETL) can be used.

FIG. 2 is a schematic sectional view of an OLED 100, according toanother exemplary embodiment of the present invention. FIG. 2 differsfrom FIG. 1 in that the OLED 100 of FIG. 2 comprises an electronblocking layer (EBL) 145 and a hole blocking layer (HBL) 155.

Referring to FIG. 2, the OLED 100 includes a substrate 110, an anode120, a hole injection layer (HIL) 130, a hole transport layer (HTL) 140,an electron blocking layer (EBL) 145, an emission layer (EML) 150, ahole blocking layer (HBL) 155, an electron transport layer (ETL) 160, anelectron injection layer (EIL) 180 and a cathode electrode 190.

FIG. 3 is a schematic sectional view of a tandem OLED 200, according toanother exemplary embodiment of the present invention. FIG. 3 differsfrom FIG. 2 in that the OLED 100 of FIG. 3 further comprises a chargegeneration layer and a second emission layer.

Referring to FIG. 3, the OLED 200 includes a substrate 110, an anode120, a first hole injection layer (HIL) 130, a first hole transportlayer (HTL) 140, a first electron blocking layer (EBL) 145, a firstemission layer (EML) 150, a first hole blocking layer (HBL) 155, a firstelectron transport layer (ETL) 160, an n-type charge generation layer(n-type CGL) 185, a hole generating layer (p-type charge generationlayer; p-type GCL) 135, a second hole transport layer (HTL) 141, asecond electron blocking layer (EBL) 146, a second emission layer (EML)151, a second hole blocking layer (EBL) 156, a second electron transportlayer (ETL) 161, a second electron injection layer (EIL) 181 and acathode 190.

While not shown in FIG. 1, FIG. 2 and FIG. 3, a sealing layer mayfurther be formed on the cathode electrodes 190, in order to seal theOLEDs 100 and 200. In addition, various other modifications may beapplied thereto.

Hereinafter, one or more exemplary embodiments of the present inventionwill be described in detail with, reference to the following examples.However, these examples are not intended to limit the purpose and scopeof the one or more exemplary embodiments of the present invention.

Experimental Part Preparation of Inventive Metal Complexes

Exemplary Compound E₂

The Compound Has Been Prepared According to Scheme 1

Step 1: Synthesis of1,1,1-trifluoro-N-(perfluorophenyl)methanesulfonamide

A 250 mL Schlenk flask was heated in vacuum and after cooling was purgedwith nitrogen. Perfluoroaniline was dissolved in 100 mL toluene and thesolution was cooled to −80° C. A 1.7 M t-Butyllithium solution was addeddropwise via syringe over 10 min. The reaction solution changed fromclear to cloudy and was stirred for 1 h at −80° C. After that, thesolution was allowed to warm to −60 ° C. and 1.1 eq oftrifluoromethanesulfonic anhydride was added dropwise to the solution.Then the cooling bath was removed and the reaction mixture was allowedto warm slowly to ambient temperature and stirred overnight, whereby thecolor changed to light orange. Additionally, a white solid formed. Theprecipitated by-product lithium trifluoromethanesulfonate was filteredoff by suction filtration over a sintered glass filter and washed with2×30 mL toluene and 30 mL n-hexane. The orange filtrate was evaporatedand dried in high vacuum forming crystals. The crude product was thenpurified by bulb-to-bulb distillation (135° C. @ 1.2×10⁻¹ mbar)resulting in a crystalline colorless solid (main fraction).

¹H NMR [d⁶-DMSO, ppm] δ: 13.09 (s, 1 H, N-H).

¹³C{¹H} NMR [d⁶-DMSO, ppm] δ: 116.75 (m, Ci-C₆F₅), 120.74 (q,¹J_(CF)=325 Hz, CF₃), 136.39, 138.35 (2 m, ²J_(CF)=247 Hz, m-C₆F₅),137.08, 139.06 (2 m, ²J_(CF)=247 Hz, p-C₆F₅), 142.98, 144.93 (2 m,²J_(CF)=247, Hz o-C₆F₅).

¹⁹F NMR [d⁶-DMSO, ppm] δ: −77.45 (m, CF₃), −148.12 (m, C₆F₅), −160.79(m, p-C₆F₅), −164.51 (m, C₆F₅).

ESI-MS: m/z-neg=314 (M-H).

EI-MS: m/z=315 (M), 182 (M-SO₂CF₃), 69 (CF₃).

Step 2: Synthesis ofbis((1,1,1-trifluoro-N-(perfluorophenyl)methyl)-sulfonamido)zinc

A 100 mL Schlenk flask was heated in vacuum and after cooling was purgedwith nitrogen. 1,1,1-Trifluoro-N-(perfluorophenyl)methanesulfonarnidewas dissolved in 10 mL toluene and 0.5 eq of diethylzinc in hexane wasadded dropwise to the solution via syringe at ambient temperature.During the addition a fog was forming and the reaction solution becamejelly and cloudy. The solution was stirred for further 30 min at thistemperature. After that, 30 mL n-hexane were added and a whiteprecipitate formed, which was filtered over a sintered glass filter(pore 4) under inert atmosphere. The filter cake was twice washed with15 mL n-hexane and dried in high vacuum at 100° C. for 2 h

Yield: 660 mg (0.95 mmol, 60% based on1,1,1-trifluoro-N-perfluorophenyl)methanesulfonamide) as a white solid.

¹³C{¹H} NMR [d⁶-DMSO, ppm] δ: 121.68 (q, ¹J_(CF)=328 Hz, CF₃), 123.56(m, Ci-C₆F₅), 133.98, 135.91 (2 m, ²J_(CF)=243 Hz, p-C₆F₅), 136.15,138.13 (2 m, ²J_(CF)=249 Hz, m-C₆F₅), 142.33, 144.24 (2 m, ²J_(CF)=240,Hz o-C₆F₅).

¹⁹F NMR [d⁶-DMSO, ppm] δ: −77.52 (m, CF₃), −150.43 (m, C₆F₅), −166.77(m, C₆F₅), −168.23 (m, p-C₆F₅).

ESI-MS: m/z-neg=314 (M-Zn-L).

EI-MS: m/z=692 (M), 559 (M-SO₂CF₃) 315 (C₆F₅NHSO₂CF₃), 182 (C₆F₅NH), 69(CF₃).

Exemplary Compound E₃

9.1 g E₂ has been sublimed at the temperature 240° C. and pressure10⁻3Pa. yield 5.9 g (65%).

The sublimed material formed colorless crystals. One crystal of anappropriate shape and size (0.094×0.052×0.043 mm³) has been closed underAr atmosphere in a glass capillary and analyzed on Kappa Apex IIdiffractometer (Bruker-AXS, Karlsruhe, Germany) with monochromatic X-rayradiation from a source provided with molybdenum cathode (λ=71.073 pm).Overall 37362 reflexions were collected within the theta range 1.881 to28.306°.

The structure was resolved by direct method (SHELXS-97, Sheldrick, 2008)and refined with a full-matrix least-squares method (SHELXL-2014/7,Olex2 (Dolomanov, 2017).

Further investigations showed that a complex having an oxygen dianioncore tetrahedrally surrounded by four Zn dications bridged with sixtrifluoracetate bidentate anionic ligands is similarly active as ap-dopant as compound E₃. This complex having composition C₁₂F₁₈O₁₃Zn₄ isobtainable by vacuum sublimation of a commercially available compoundhaving CAS number 1299489-47-6 and according to XRD analysis of amonocrystal obtained by sublimation, it may form a trigonal crystallattice belonging to the space group R-3c, with unit cell dimensions atthe temperature 296 K a=23.376(6) Å, α=59.989(10)°; b=23.376(6) Å,β=59.989(10)°; c=23.376(6) Å; Y=59.989(10)°.

In the solid crystalline phase, the number of molecules having thechemical formula C₁₂F₁₈O₁₃Zn₄and comprised in the unit cell of thecrystal lattice may be Z=12.

In the solid crystalline phase, the unit cell volume at temperature 296K may be 9030(7) Å³ and calculated density may be 2.109 g/cm³.

Device Experiments Generic Procedures

OLEDs with two emitting layers were prepared to demonstrate thetechnical benefit of an organic electronic device comprising a holeinjection layer and/or a hole generating layer according to the presentinvention. As proof-of-concept, the tandem OLEDs comprised two blueemitting layers.

A 15Ω/cm² glass substrate with 90 nm ITO (available from Corning Co.)was cut to a size of 150 mm×150 mm×0.7 mm, ultrasonically cleaned withisopropyl alcohol for 5 minutes and then with pure water for 5 minutes,and cleaned again with UV ozone for 30 minutes, to prepare a firstelectrode.

The organic layers are deposited sequentially on the ITO layer at 10⁻⁵Pa, see Table 1 and 2 for compositions and layer thicknesses. In theTables 1 to 3, c refers to the concentration, and d refers to the layerthickness.

Then, the cathode electrode layer is formed by evaporating aluminum atultra-high vacuum of 10⁻⁷ mbar and deposing the aluminum layer directlyon the organic semiconductor layer. A thermal single co-evaporation ofone or several metals is performed with a rate of 0, 1 to 10 nm/s (0.01to 1 Å/s) in order to generate a homogeneous cathode electrode with athickness of 5 to 1000 nm. The thickness of the cathode electrode layeris 100 nm.

The device is protected from ambient conditions by encapsulation of thedevice with a glass slide. Thereby, a cavity is formed, which comprisesa getter material for further protection.

Current voltage measurements are performed at the temperature 20° C.using a Keithley 2400 source meter, and recorded in V.

Experimental Results Materials Used in Device Experiments

The formulae of the supporting materials mentioned below are as follows:

F1 is

biphenyl-4-yl(9,9-diphenyl-9H-fluoren-2-yl)-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-amine,CAS 1242056-42-3;

F2 is

(3-(dibenzo[c,h]acridin-7-yl)phenyl)diphenylphosphine oxide, CAS1440545-22-1;

F3 is

2,4-diphenyl-6-(3′-(triphenylen-2-yl)-[1,1′-biphenyl]-3-yl)-1,3,5-triazine,CAS 1638271-85-8;

F4 is

1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene, CAS 721969-94-4;

PD-2 is

4,4′,4″-((1E,′E,1″E)-cyclopropane-1,2,3-triylidenetris(cyanomethanylylidene))tris(2,3,5,6-tetrafluorobenzonitrile), CAS1224447-88-4.

LiQ is lithium 8-hydroxyquinolinolate; ZnPc is zinc phtalocyanine;

ABH-113 is an emitter host and NUBD-370 and DB-200 are blue fluorescentemitter dopants, all commercially available from SFC, Korea.

ITO is indium tin oxide.

Standard Procedures

Voltage Stability

OLEDs are driven by constant current circuits. Those can supply aconstant current over a given voltage range. The wider the voltagerange, the wider the power losses of such devices. Hence, the change ofdriving voltage upon driving needs to be minimized.

The driving voltage of an OLED is temperature dependent. Therefore,voltage stability needs to be judged in thermal equilibrium. Thermalequilibrium is reached after one hour of driving.

Voltage stability is measured by taking the difference of the voltageafter 50 hours and after 1 hour driving at a constant current density.Here, a current density of 30 mA/cm² is used. Measurements are done atroom temperature.

dU[V]=U(50 h, 30 mA/cm²)−U(1 h, 30 mA/cm²)

Example 1

Use of an inverse coordination complex as a neat hole injection layer ina blue OLED

Table 1a schematically describes the model device.

TABLE 1a c d Material [wt %] [nm] ITO 100  90 B2 or E3 100   3* F1 100120 ABH113:NUBD370 97:3   20 F2:LIQ 50:50  36 Al 100 100 *E3 has beentested also as a layer only 1 nm thin.

The results are given in Table 1b

TABLE 1b *j = 15 mA/cm² U* EQE* U(50 h) − U(1 h)** **j = 30 mA/cm² [V][%] CIE-y* [V] 3 nm B2 5.28 6.6 0.090 0.275 (reference) 3 nm E3 5.38 5.70.094 0.246 1 nm E3 5.11 5.4 0.096 0.040

This example shows that inverse coordination complexes are useful as aneat HIL comprised in an OLED.

Example 2

Use of an inverse coordination complex as a p-dopant a hole injectionlayer comprised in a blue OLED

Table 2a schematically describes the model device.

TABLE 2a c d Material [wt %] [nm] ITO 100 90 F1:p-dopant 92:8 10 (mol%#) F1 100 120 ABH113:NUBD370 3 20 F2:LiQ 50 36 Al 100 100 #based onmolar amount of metal atoms

The results are given Table 2b

TABLE 2b *j = 15 mA/cm² U* EQE* U(50 h) − U(1 h)** **j = 30 mA/cm² [V][%] CIE-y* [V] B2 8.06 7.1 0.095 0.639 (reference) E3 5.15 5.7 0.094−0.015

This example shows that inverse coordination complexes are us p-dopantsfor a HIL comprising a hole transport matrix.

Blue OLED comprising B2 coordination complex as a p-dopant in a neathole injection layer combined with a p-doped hole injection layer.

Example 3

Blue tandem OLED comprising an inverse coordination complex as a neathole generation layer

Table 3a schematically describes the model device.

TABLE 3a c d Material [wt %] [nm] ITO 100 90 F1:PD-2 92:8 10 F1 100 145ABH113:BD200 97:3 20 F3 100 26 F4:Li 99:1 10 ZnPc 100 2 p-dopant 100 1F1 100 30 ABH113:BD200 97:3 20 F3 100 26 F4:Li 99:1 10 Al 100 100

The results are given in Table 3b

TABLE 3b *j = 10 mA/cm² U* EQE* **j = 30 mA/cm² [V] [%] CIE-y* 1 nm B210.65 6.3 0.066 (reference) 1 nm E3 7.52 13.5 0.083

The results show that inverse coordination complexes might be suitableas a neat CGL.

Example 4

Blue tandem OLED comprising an inverse coordination complex as ap-dopant in a hole generation layer

Table 4a schematically describes the model device.

TABLE 4a c d Material [wt %] [nm] ITO 100 90 F1:PD-2 92:8 10 F1 100 145ABH113:BD200 97:3 20 F3 100 25 F4:Li 99:1 10 ZnPc 100 2 F1:p-dopant 84:16 10 (mol %)# F1 100 30 ABH113:BD200 97:3 20 F3 100 26 F4:Li 99:110 Al 100 100 #based on molar amount of metal atoms

The results are given in Table 4b

TABLE 4b *j = 10 mA/cm² U* EQE* U(50 h) − U(1 h)** **j = 30 mA/cm² [V][%] CIE-y* [V] B2 8.98 13.4 0.082 (reference) E3 7.75 14.2 0.087 0.094

The results demonstrate that inverse metal complexes may be useful alsoin this embodiment of a tandem OLED.

From the foregoing detailed description and examples, it will be evidentthat modifications and variations can be made to the compositions andmethods of the invention without departing from the spirit and scope ofthe invention. Therefore, it is intended that all modifications made tothe invention without departing from the spirit and scope of theinvention come within the scope of the appended claims.

1. Organic electronic device comprising at least one inversecoordination complex, the inverse coordination complex comprising: acore consisting of one atom or of a plurality of atoms forming togethera covalent cluster; (ii) a first coordination sphere consisting of atleast four electropositive atoms having each individually anelectronegativity according to Allen of less than 2.4; and (iii) asecond coordination sphere comprising a plurality of ligands; whereinthe first coordination sphere is closer to the core than the secondcoordination sphere; all atoms of the core have a higherelectronegativity according to Allen than any of the electropositiveatoms of the first coordination sphere; and at least one ligand of thesecond coordination sphere is covalently bound to at least two atoms ofthe first coordination sphere.
 2. Organic electronic device according toclaim 1, wherein the electropositive atoms of the first coordinationsphere are independently selected from atoms having an electronegativityaccording to Allen of less than 2.3.
 3. Organic electronic deviceaccording to claim 1, wherein the electropositive atoms areindependently selected from metal ions in the oxidation state (II). 4.Organic electronic device according to claim 1, wherein the coreconsists of one atom which is O in the oxidation state (-II).
 5. Organicelectronic device according to claim 1, wherein the first coordinationsphere consists of four electropositive atoms having anelectronegativity according to Allen of less than 2.4, respectively inthe oxidation state (II), and the four electropositive atoms aretetrahedrally coordinated to the core.
 6. Organic electronic deviceaccording to claim 1, wherein at least one ligand of the secondcoordination sphere is a bidentate anionic ligand formed bydeprotonation of an alpha-gamma tautomerizable protic acid and bridgingtwo electropositive atoms of the first coordination sphere.
 7. Organicelectronic device according to claim 16, wherein the core consists ofone chalcogen atom selected from O, S, Se and Te in the oxidation state(-II); the first oxidation sphere consists of four electropositive atomswhich are four metal atoms in the oxidation state (II) and which aretetrahedrally coordinated to the core, and the second coordinationsphere consists of six ligands having the general formula (I). 8.Organic electronic device according to claim 7, wherein each ligand ofthe second coordination sphere is coordinated to two different metalatoms of the first coordination sphere.
 9. Organic electronic deviceaccording to claim 1 comprising, between a first electrode and a secondelectrode, an organic semiconducting layer comprising the at least oneinverse coordination complex.
 10. Organic electronic device according toclaim 9, wherein the organic semiconducting layer is a charge injectionlayer, a charge transport layer or a charge generation layer. 11.Organic electronic device according to claim 9, wherein the organicsemiconducting layer is a hole injection layer, a hole transport layeror a hole generation layer.
 12. Organic electronic device according toclaim 9, wherein the organic semiconducting layer further comprises atleast one organic matrix compound.
 13. Organic electronic deviceaccording to claim 1, wherein the organic electronic device is anelectroluminescent device.
 14. Organic electronic device according toclaim 1, wherein the electroluminescent device is an organic lightemitting diode.
 15. Method for preparing an organic electronic deviceaccording to claim 1, the method comprising the steps of (a) evaporatingthe inverse coordination complex; and (b) depositing the inversecoordination complex on a solid support.
 16. Organic electronic deviceaccording to claim 6, wherein the at least one ligand is a carboxylateanion or is represented by the general formula (I)

wherein R¹ and R² are independently selected from the groups, consistingof C₁ to C₃₀ hydrocarbyl groups and C₂ to C₃₀ heterocyclic group,wherein R¹ and/ or R² may optionally be substituted with at least one ofCN, F, Cl, Br and I.